#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>

int main(int argc, char const *argv[])
{
    int ret = -1;
    int fd = -1;
    ret = mkfifo("fifo",0664);
    if (errno != 17){
        printf("mkfifo failed\n");
        return -1;
    }else {
        printf("fifo is existing\n");
    }

    fd = open("fifo",O_)
    return 0;
}